Hair straightener



FIG. 1 is a perspective view from above to the right of the hair straightener, which is the subject of my new design in an open position;

FIG. 2 is a perspective view from above and to the right of the hair straightener in the closed position;

FIG. 3 is a top plan view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a left side elevational view thereof;

FIG. 6 is a right side elevational view thereof;

FIG. 7 is a front elevational view thereof; and,

FIG. 8 is a rear elevational view thereof. 

The ornamental design for a hair straightener, as shown and described. 